1. Field of Invention
This invention relates to surgical devices, and more particularly, to surgically implantable bone support devices used to fuse bone structures.
2. Description of Related Art
Unfortunately, some patients suffer from various problems which require at least a portion of an ankle joint to be effectively immobilized. This is traditionally done by inserting one or more rigid rods or pins (typically made of stainless steel or titanium and having a diameter roughly the size of a patient's finger) into one or more bones in the ankle, and in the portion of the foot which includes the heel. This permanently affixes certain bones to other bones. The medical term for this type of permanent bone fixation is “arthrodesis”.
While arthrodesis severely limits flexibility and mobility within the ankle joint, it sometimes becomes necessary as a treatment for conditions such as severe arthritis, infection and/or avascular necrosis of one or more bones in the region, congenital deformity of the tibio-talar or talocalcaneal joint, diabetic charcot foot or certain types of neuropathy. For these conditions, any motion of the bones relative to each other can cause severe pain in the foot or ankle, to a point where a patient becomes effectively unable to walk or put any pressure on that foot. Accordingly, immobilization of the ankle joint becomes an acceptable price to pay if the patient can begin to walk again without excruciating pain in the ankle and foot.
A bone plate is a plate that is traditionally fastenable to the surface of a fractured bone to support and/or stabilize the fracture as the bone heals. Bone plates may be attached to the bone with bone screws that extend from the plate into the bone. In some examples, the head of the bone screw is locked to the plate (e.g., by threaded engagement between the screw head and the bone plate) and in other plates the angle of the head of the screw is free to shift with respect to the plate, such that the screw may be placed in the bone at a surgeon-selected angle. In yet other examples, the screw head may cooperate with the bone plate to provide compression or distraction of the fracture
Previously, problems of bone fixation have been addressed only in separate methods such as the use of internal rod or locking plate technology, which have been available for years in orthopedics. In other words, the current technology only contemplates either rods with locking screws, or plates with locking screws for fixation. These technologies are applied in one dimension, as no common approach has incorporated multiple techniques in three dimensions, regardless of a long-term need to immobilize the ankle joint.
The inventor has discovered that these existing approaches for bone fixation may still provide insufficient support for bone fusions, reconstructions and fracture management in the lower extremity (e.g., foot and ankle region). According the inventor has created an optimal single stable construct for ambulation by providing rods that lock together and use locking screws for internal fixation.